Apparatus and methods for processing blood

ABSTRACT

Apparatus and methods for processing blood are disclosed in which one variation generally comprises a tube defining a channel and an access tube extending into the channel. An open cell matrix configured to entrap red blood cells may be positioned within at least a portion of the channel. Another variation generally comprises a cylindrical tube and a plunger slidably positioned within the channel. The plunger also has a funnel positioned upon the plunger and is movable therewith. Both the plunger and funnel define a fluid channel through and in communication with the cylindrical tube.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.16/450,669 filed Jun. 24, 2019, which claims the benefit of priority toU.S. Prov. 62/695,649 filed Jul. 9, 2018, each of which is incorporatedherein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to apparatus and methods for separatingblood components. More particularly, the present invention relates toapparatus and methods for effectively separating and removing specificcomponents from blood.

BACKGROUND OF THE INVENTION

Blood may be fractionated and the different fractions of the blood usedfor different medical needs. For instance, anemia (low erythrocytelevels) may be treated with infusions of erythrocytes. Thrombocytopenia(low thrombocyte (platelet) levels) may be treated with infusions ofplatelet concentrate.

The sedimentation of the various blood cells and plasma is based on thedifferent specific gravity of the cells and the viscosity of the medium.When sedimented to equilibrium, the component with the highest specificgravity (density) eventually sediments to the bottom, and the lightestrises to the top. Under the influence of gravity or centrifugal force,blood spontaneously sediments into three layers. At equilibrium the top,low-density layer is a straw-colored clear fluid called plasma. Plasmais a water solution of salts, metabolites, peptides, and many proteinsranging from small (insulin) to very large (complement components).Plasma per se has limited use in medicine but may be furtherfractionated to yield proteins used, for instance, to treat hemophilia(factor VIII) or as a hemostatic agent (fibrinogen). The term plateletrich plasma (PRP) is used for this component because most of the plasmaproteins and platelets in the whole blood are in the plasma followingslow centrifugation so the concentration of platelets in the plasma hasincreased while suspended in supernatant plasma. The uppermost layerafter centrifugation typically contains plasma proteins only and istypically called platelet-poor plasma (PPP) due to the absence or lownumber of platelets as a result of a “hard spin”.

The bottom, high-density layer is a deep red viscous fluid comprisingnuclear red blood cells (RBC) specialized for oxygen transport. The redcolor is imparted by a high concentration of chelated iron or heme thatis responsible for the erythrocytes high specific gravity. Packederythrocytes, matched for blood type, are useful for treatment of anemiacaused by, e.g., bleeding. The relative volume of whole blood thatconsists of erythrocytes is called the hematocrit, and in normal humanbeings can range from about 38% to about 54%.

The intermediate layer is the smallest layer, appearing as a thin whiteband on top the erythrocyte layer and below the plasma, and is calledthe buffy coat. The buffy coat itself has two major components,nucleated leukocytes (white blood cells) and anuclear smaller bodiescalled platelets (or thrombocytes). Leukocytes confer immunity andcontribute to debris scavenging. Platelets seal ruptures in the bloodvessels to stop bleeding and deliver growth and wound healing factors tothe wound site. The buffy coat may be separated from whole blood whenthe blood is subjected to a “hard spin” in which the whole blood is spunhard enough and long enough so that platelets sediment from plasma ontopacked red cells and white cells percolate up through red cell pack tothe interface between red cells and plasma.

When whole blood is centrifuged at a low speed (e.g., up to 1,000 g) fora short time (e.g., two to four minutes) white cells sediment fasterthan red cells and both sediment much faster than platelets. At higherspeeds the same distribution is obtained in a shorter time. The methodof harvesting PRP from whole blood is based on this principle.Centrifugal sedimentation that takes the fractionation only as far asseparation into packed erythrocytes and PRP is called a “soft spin”which is typically used to describe centrifugation conditions underwhich erythrocytes are sedimented but platelets remain in suspension.“Hard spin” is typically used to describe centrifugation conditionsunder which erythrocytes sediment and platelets sediment in a layerimmediately above the layer of erythrocytes.

The auto-transfusion equipment used to make autologous plateletconcentrates requires a skilled operator and considerable time andexpense and these devices require a large prime volume of blood. Whilemany of these devices have somewhat reduced the cost and the timerequired, skilled operators and time are still required. Accordingly,there remains a need for simple and effective methods and devices forseparating and removing components from whole blood.

SUMMARY OF THE INVENTION

The present invention relates to apparatus and methods for rapidfractionation of blood into its different components, e.g., erythrocyte,plasma, and platelet fractions. The devices and methods described haveparticular value for rapid preparation of autologous concentratedplatelet fractions, e.g., to help or speed healing.

In separating out the fractional layers from blood, one variation mayinclude a centrifuge tube fitted with an access tube extending withinand having a predefined length for withdrawing the fractional layers. Acentrifuge tube may include an access tube extending within the channelof the tube from a cover or seal. The access tube may be fluidly coupledto a septum luer through which a line or syringe may be attached. In onevariation, the access tube length may be about half of the centrifugetube length so that the opening of the access tube may be suitablypositioned to withdraw specified fractional layers of the separatedblood. In one example, whole blood may be received within the centrifugetube and sealed with the access tube extending within the blood.Alternatively, the blood may be introduced into the tube directlythrough the access tube and the tube may be subsequently sealed.Anticoagulants may be preloaded within the centrifuge tube or introducedinto the tube along with the blood.

The centrifuge tube may be then subjected to a centrifuge or left toseparate under the force of gravity. The resulting fractional layerswill form within the tube with the RBC layer formed in the lower portionof centrifuge tube. The PRP layer will remain suspended above thesedimented RBC layer and with the length of the access tube properlysized, the opening will remain within the PRP layer. The blood cell-freePRP layer can then be recovered by withdrawal back into the syringe viathe access tube. The process time can be reduced dramatically by brieflyspinning the anticoagulated blood to pellet the blood cells.

If desired, an optional layer of a matrix, such as open cell foam,fabric mat, or other open matrix, can occupy the lower portion of thetube to entrap the sedimented blood cells and reduce the risk ofdisturbing the settled cells during handling.

In yet another variation, a cylindrical tube may have a closed floor anda plunger having a funnel attached. A plunger opening may be definedthrough the plunger and a length of tubing having an opening may beconnected to the apex of the funnel. Rather than having a plunger pushedthrough the channel of the tube from an end opposite of where thefractional layer is removed, the plunger and funnel may be used toremove the fractional layer from the same end of where the plunger isactuated. In this manner, the plunger is pushed down into the tube andtowards the floor rather than from the bottom of the tube away from thefloor.

One variation of a method for separating blood into its fractionallayers and then withdrawing specific layers using the tube may have theplunger and attached funnel initially positioned at the closed floor ofthe tube. The tubing may be seen extend from the funnel through the tubeand terminating at the opening positioned externally of the tube. Asyringe containing a volume of blood, e.g., anticoagulated blood, may beconnected to the opening and then injected through the tubing, into thefunnel, through the plunger, and into the tube which may force theplunger and funnel away from the floor as the blood enters the tube.

Once the tube has been sufficiently filled with the blood, the tubingmay be detached from the top of the funnel which may be secured with acap or seal in preparation for centrifugation with the funnel remainingin place upon the plunger. Once the tube and blood has been sufficientlycentrifuged, the blood may have fractionalized into its componentlayers, e.g., a first PRP layer and a second RBC layer.

A tubing connected to a withdrawal syringe may be coupled to the funneland the syringe may be used to draw the PRP layer directly through thefunnel and into the syringe. Due to the vacuum drawn via the withdrawalsyringe, the plunger and funnel may be forced to move further into thetube and towards the floor as the PRP layer is removed from the tube.

During withdrawal, because the plunger and funnel are moving into thePRP layer for collection, the platelets within the layer are no longerdragged against the walls of the tubing. Moreover, because the PRP layer(buffy coat, RBC layer) remains undisturbed until contacted with thefunnel, the yield on platelets and white blood cells are potentiallyimproved while contamination from the RBC layer is potentially reduced.

One variation of a separation apparatus generally comprises a tubehaving a first length and defining a channel within, an access tubehaving a second length and extending into the channel, and an open cellmatrix configured to entrap red blood cells and positioned within atleast a portion of the channel, wherein the access tube defines anopening which is positioned within proximity of the open cell matrixwithin the channel.

Another variation of a separation apparatus generally comprises acylindrical tube defining an opening and a channel extendingtherethrough, a plunger defining a plunger fluid opening and slidablypositioned within the channel, and a funnel positioned upon the plungerand movable therewith, wherein the funnel defines a funnel fluid openingin fluid communication with the plunger fluid opening.

One variation for a method of separating components from blood generallycomprises introducing a volume of blood through a funnel and a plungerand into a channel defined by a cylindrical tube such that the funneland plunger are moved from a first position within the tube to a secondposition in proximity to an opening defined by the tube, applying acentrifugal force to the volume of blood contained within the tube suchthat the blood forms at least a first fractional layer and a secondfractional layer, and withdrawing at least the first fractional layerfrom the tube via the funnel and the plunger such that the funnel andplunger are moved from the second position back towards the firstposition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of one variation of a separationassembly having an access tube extending at least partially into thecentrifuge tube.

FIG. 2A shows a perspective view of another variation of the separationassembly having an access tube and a matrix for retaining specific bloodcomponents.

FIGS. 2B and 2C show side views of additional variations of theseparation assembly having a matrix contained within.

FIG. 3 shows a perspective view of another variation of a separationassembly having a funnel-shaped plunger assembly

FIGS. 4A to 4G show an example of the separator assembly having thefunnel-shaped-plunger used to separate and selectively collect thedifferent blood components.

DETAILED DESCRIPTION OF THE INVENTION

Throughout the description, terms such as “top”, “above, “bottom”,“below” are used to provide context with respect to the relativepositioning of components when, e.g., a container tube with fractionalcomponents of blood are positioned when the longitudinal axis of acontainer tube is positioned upright or non-horizontally. Suchdescription is used for illustrative purposes only.

As discussed herein, when sedimented to equilibrium, the component withthe highest specific gravity (density) eventually sediments to thebottom, and the lightest rises to the top. Under the influence ofgravity or centrifugal force, blood spontaneously sediments into threelayers. At equilibrium the top, low-density layer is a straw-coloredclear fluid called plasma. The term platelet rich plasma (PRP) is usedfor this component because most of the plasma proteins and platelets inthe whole blood are in the plasma following slow centrifugation so theconcentration of platelets in the plasma has increased while suspendedin supernatant plasma. The bottom, high-density layer comprisessedimented red blood cells (RBC). The intermediate layer, if the bloodis subjected to further centrifugation, is called the buffy coat.

Sedimentation Matrix

In separating out the fractional layers from blood, one variation mayinclude a centrifuge tube fitted with an access tube extending withinand having a predefined length for withdrawing the fractional layers.Because blood typically contains about 40% to 45% of red blood cells byvolume, the resulting volume of the RBC layer after centrifugation canbe determined relative to the height of the centrifugation tube.

FIG. 1 shows a variation in which the centrifuge tube 10 may include anaccess tube 12 extending within the channel of the tube 10 from a coveror seal 14. The access tube 12 may be fluidly coupled to a septum Luer16 through which a line or syringe 18 may be attached. The access tube12 may have a predefined access tube length L_(A) which is less than thecentrifuge tube length L_(T), as shown. In one variation, the accesstube length L_(A) may be about half of the centrifuge tube length L_(T).In other variations, the access tube length L_(A) may range between,e.g., 30 to 50% of the centrifuge tube length L_(T).

With the opening 20 of the access tube 12 positioned approximatelyhalf-way down the length of the centrifuge tube 10, the opening 20 maybe suitably positioned to withdraw specified fractional layers of theseparated blood. In one example, whole blood may be received within thecentrifuge tube 10 and sealed with the access tube 12 extending withinthe blood. Alternatively, the blood may be introduced into the tube 10directly through the access tube 12 and the tube may be subsequentlysealed. Anticoagulants may be preloaded within the centrifuge tube 10 orintroduced into the tube 10 along with the blood.

The centrifuge tube 10 may be then subjected to a centrifuge or left toseparate under the force of gravity. The resulting fractional layerswill form within the tube 10 with the RBC layer formed in the lowerportion of centrifuge tube 22. The PRP layer will remain suspended abovethe sedimented RBC layer and with the length of the access tube 12properly sized, the opening 20 will remain within the PRP layer. Theblood cell-free PRP layer can then be recovered by withdrawal back intothe syringe 18 via the access tube 12. The process time can be reduceddramatically by briefly spinning the anticoagulated blood to pellet theblood cells.

If desired, an optional layer of a matrix 24, such as open cell foam,fabric mat, or other open matrix, can occupy the lower portion 22 of thetube 10 to entrap the sedimented blood cells and reduce the risk ofdisturbing the settled cells during handling. FIG. 2A shows aperspective view of a tube 10 having the access tube 12 extending withinto about half the length of the tube 10 such that the opening 20 ispositioned above the matrix 24. The matrix 24 is shown as an open cellfoam having defined pores which are large enough so that the red bloodcells and white blood cells can penetrate into and become entrappedwithin the matrix 24 when the tube 10 is centrifuged. The PRP layer mayremain suspended in the plasma fraction above the entrapped RBC layerfor subsequent withdrawal through the access tube 12.

FIGS. 2B and 2C show partial cross-sectional side views of the tube 10having alternative features to the matrix 24. The variation of FIG. 2Bmay incorporate a shelf 26 which functions as a stop for preventing thesedimented RBC layer from becoming disturbed. FIG. 2C shows anothervariation in which the matrix or foam 26 only partially fills the lowerportion of the tube 10. For instance, the matrix or foam 26 may beformed into a disk or cylindrical shape positioned at approximatelymid-height of the tube 10 just below the opening 20 of the access tube12.

Inverse Plunger

In yet another variation, FIG. 3 shows a perspective view of acylindrical tube 30 having a closed floor 32 and a plunger 34 having afunnel 36 attached. A plunger opening 38 may be defined through theplunger 34 and a length of tubing 40 having an opening 42 may beconnected to the apex of the funnel 36. In other variations, the plunger34 and funnel 36 may be formed into a single integrated or uniformcomponent having a single channel defined through the component betweenthe plunger opening 38 and a funnel opening. As shown, rather thanhaving a plunger pushed through the channel of the tube 30 from an endopposite of where the fractional layer is removed, the plunger 34 andfunnel 36 may be used to remove the fractional layer from the same endof where the plunger 34 is actuated. In this manner, the plunger 34 ispushed down into the tube 30 and towards the floor 32 rather than fromthe bottom of the tube 30 away from the floor 32.

FIGS. 4A to 4G show one variation of a method for separating blood intoits fractional layers and then withdrawing specific layers using thetube 30. As shown in FIG. 4A, the tube 30 may have the plunger 34 andattached funnel 36 initially positioned at the closed floor 32 of thetube 30. The tubing 40 may be seen extend from the funnel 36 through thetube 30 and terminating at the opening 42 positioned externally of thetube 30. A syringe 44 containing a volume of blood 46, e.g.,anticoagulated blood, may be connected to the opening 42, as shown inFIG. 4B, and then injected through the tubing 40, into the funnel 36,through the plunger 34, and into the tube 30 which may force the plunger34 and funnel 36 away from the floor 32 as the blood enters the tube 30,as shown in FIG. 4C.

Once the tube 30 has been sufficiently filled with the blood 46, thetubing 40 may be detached from the top of the funnel 36 which may besecured with a cap or seal 48 in preparation for centrifugation, asshown in FIG. 4D, with the funnel 36 remaining in place upon the plunger34. Once the tube 30 and blood 46 has been sufficiently centrifuged, theblood 46 may have fractionalized into its component layers, e.g., afirst PRP layer 46′ and a second RBC layer 46″, as shown in FIG. 4E.

A tubing 50 connected to a withdrawal syringe 52 may be coupled to thefunnel 36, as shown in FIG. 4F, and the syringe 52 may be used to drawthe PRP layer 46′ directly through the funnel 36 and into the syringe52. Due to the vacuum drawn via the withdrawal syringe 52, the plunger34 and funnel 36 may be forced to move further into the tube 30 andtowards the floor 32 as the PRP layer 46′ is removed from the tube 30,as shown in FIG. 4G.

During withdrawal, because the plunger 34 and funnel 36 are moving intothe PRP layer 46′ for collection, the platelets within the layer 46′ areno longer dragged against the walls of the tubing 30. Moreover, becausethe PRP layer (buffy coat, RBC layer) remains undisturbed untilcontacted with the funnel 36, the yield on platelets and white bloodcells are potentially improved while contamination from the RBC layer ispotentially reduced.

For discussion purposes, a “hard spin” generally refers to the firstspin in the double-centrifugation protocol for separating the red bloodcells from the plasma while a “soft spin” generally refers to the secondspin in the protocol which is used to further separate the platelets,white blood cells and few remaining red blood cells from the plasma.While not intended to be limiting, a “hard spin” may range, e.g.,between 2000 to 4000×g over 2 to 20 minutes, while a “soft spin” mayrange, e.g., between 500 to 1000×g over 2 to 20 minutes.

In the case where the whole blood 46 has been subjected to a “softspin”, the fractionalized PRP layer may be withdrawn using the methoddescribed. In the case where the whole blood 46 has been subjected to a“hard spin”, an additional fractional layer of platelet-poor plasma(PPP) may be formed atop of the PRP layer. The plunger 34 and funnel 36may be partially translated through the tube 30 and towards the floor 32to capture just the PPP layer, the PRP layer, or both, if desired. Inthe case where a buffy coat has been formed after a “hard spin”, oncethe PRP layer has been withdrawn, a second withdrawal syringe may beconnected and the buffy coat alone may then be withdrawn into the secondwithdrawal syringe.

The apparatus and methods disclosed above are not limited to theindividual embodiments which are shown or described but may includecombinations which incorporate individual features between the differentvariations. Modification of the above-described assemblies and methodsfor carrying out the invention, combinations between differentvariations as practicable, and variations of aspects of the inventionthat are obvious to those of skill in the art are intended to be withinthe scope of the claims.

What is claimed is:
 1. A method of separating components from blood,comprising: introducing a volume of blood through a funnel and a plungerand into a channel defined by a cylindrical tube such that the funneland the plunger are moved from a first position within the cylindricaltube to a second position where a funnel fluid opening is positionedexternally of an opening defined by the cylindrical tube; applying acentrifugal force to the volume of blood contained within thecylindrical tube such that the blood forms at least a first fractionallayer and a second fractional layer; and withdrawing at least the firstfractional layer from the cylindrical tube via the funnel and theplunger such that the funnel and the plunger are moved from the secondposition back towards the first position away such that the funnel fluidopening is positioned within an interior of the cylindrical tube whilethe first fractional layer is withdrawn into the funnel through a firstwidth and into contact with the funnel and out of the funnel fluidopening through a second width which is smaller than the first width viaa vacuum force formed within the funnel.
 2. The method of claim 1further comprising introducing an anticoagulant into the cylindricaltube.
 3. The method of claim 1 wherein introducing the volume of bloodcomprises introducing the volume of blood through a tubing attached tothe funnel fluid opening.
 4. The method of claim 3 further comprisingremoving the tubing from the funnel fluid opening prior to applying thecentrifugal force.
 5. The method of claim 1 wherein applying acentrifugal force comprises forming the first fractional layer comprisedof a PRP layer.
 6. The method of claim 1 wherein applying a centrifugalforce comprises forming the second fractional layer comprised of a RBClayer.
 7. The method of claim 1 wherein withdrawing at least the firstfractional layer comprises suctioning the first fractional layer via awithdrawal syringe fluidly coupled to the funnel.
 8. The method of claim7 further comprising withdrawing an additional fractional layer via asecond withdrawal syringe fluidly coupled to the funnel.